The present invention relates to a centerline determining apparatus for determining a centerline of a body, a medical apparatus for determining a centerline of a body, and a program applied to the centerline determining apparatus.
Magnetic resonance imaging apparatuses for imaging a subject using a contrast medium have been conventionally known.
An example of the method of imaging a subject using a contrast medium is one in which an operator visually finds a position of an aorta from within/among an image/images, and defines a tracker region for detecting the contrast medium at the position of the aorta.
An axial image of a cross section passing through a torso, a left arm, and a right arm of a subject is produced, and the axial image is binarized. By binarizing the axial image, a binary image is obtained. In the binary image, a region of the torso, a region of the left arm, and a region of the right arm in the subject are assigned with a logical value of one, while the outside of the body of the subject is assigned with a logical value of zero. After obtaining the binary image, erosion processing, region growing, and dilation processing are repeated to thereby achieve separation processing of separating the region of the left arm and region of the right arm from the region of the torso. Therefore, by performing the separation processing, a binary image in which the regions of the arms are separated from the region of the torso may be obtained. After performing the separation processing, extraction processing of extracting the region of the torso from the separation-processed binary image is executed to obtain a binary image in which the region of the torso is extracted. Next, a centerline in a right-left direction of the body of the subject is located based on the extraction-processed binary image. The located centerline of the body is then used to detect a position of a cerebrospinal fluid, and an aorta is detected based on the detected position of the cerebrospinal fluid. Since the aorta lies near the cerebrospinal fluid, the aorta may be detected by this prior art method.
The separation processing, however, sometimes fails to separate a region of one arm of the regions of the right and left arms from the region of the torso. In this case, the region of one arm connects with the region of the torso in the separation-processed binary image, so that when extraction processing is applied to the separation-processed binary image, the region extraction is applied to the region of the torso connected with the region of one arm. Therefore, when attempting to locate a centerline of a body based on the extraction-processed binary image, the located centerline of the body is offset toward the region of one arm with respect to an actual centerline of the body, which makes it difficult to detect a position of the cerebrospinal fluid. This results in a problem that a position of the aorta cannot be correctly detected.
It is therefore desirable to provide a technique capable of locating a centerline of a body with sufficient precision even in the case that a region that should not be extracted is wrongly extracted.